Satan:
When He was still as Lucifer.
He knew that his plan will succeed as far as Adam,through Eve, but when he won Adam he wasn't aware that he lost Eve,and after also the battle as soon as Seth was born although he was unaware of.With the birth of Mary,he was shocked,as he realized that he lost Eve in order to acquire Adam.He went after Mary with the hope to prevent Mary to give birth to the second Adam. Convinced that he succeeded,he was only aware of, at the very end that it seemed more likely his end instead of becoming like the most high.which eventually what did happen!
God bless